Heat dissipation structure

ABSTRACT

A heat dissipation structure mounted onto an electronic element to dissipate heat. The heat dissipation structure includes a heat absorber connected with the electronic element and a heat sink. The heat absorber has a hollow first chamber to hold a working fluid. The heat absorber and heat sink are interposed by a plurality of first conduits. When the heat absorber absorbs heat generated by the electronic element through a contact surface, the working fluid held therein is vaporized into vapor. The vapor enters a second chamber of the heat sink through the first conduits and performs heat exchange with a cooling surface of the heat sink to be converted into the working fluid again. The working fluid is conveyed via a capillary structure in the second conduit to the first chamber to form a thermal cycle. The structure of the invention is simpler and can rapidly absorb and dissipate heat.

FIELD OF THE INVENTION

The present invention relates to a heat dissipation structure and particularly to an improved heat dissipation structure having a capillary structure.

BACKGROUND OF THE INVENTION

Advance of technology brings great benefits to people's life and constantly enhances functionality and performance of electric appliances. For instance, high-level electronic products stressed on processing speed and reliability such as server and workstation, and even personal computer and notebook computer, have promoted higher performance and speed requirement for CPU. In such developing trends, one of the biggest obstacles is heat generation. At present, the most common cause of malfunction or damage of electronic elements is poor heat dissipation that results in overheating. Heat is mainly generated by active elements such as transistors in IC during processing. The more transistors included in chips, the greater heat generated. However, the size of electronic products is shrunk constantly. With the chip area not increased at the same time, heat dissipation area decreases gradually and heat generation intensity increases. Conventional heat dissipation modules cannot meet this requirement. Overheated problem has become a bottleneck of electronic element technology development.

Heat dissipation always is an important factor needed to be taken into account in the design of an electronic system. The purpose is to reduce the probability of malfunction or damage of electronic elements caused by overheating. This not only enhances the reliability of an electronic product, but also prolongs the lifespan thereof. Research reports show that temperature increases every 10-15° C., the lifespan of chips will be shortened 50%. Hence how to rapidly dissipate the heat generated in the electronic elements is one of the main subjects for research. Take CPU in a computer for an example, the cooling method now adopted is to install an air fan or heat sink on the CPU to directly dissipate the heat. But the air fan employs compulsory convection for cooling and creates many problems, such as power consumption, noise generation and shorter lifespan. Thus other approaches have been proposed such as using a heatpipe to transmit the heat generated by the CPU to the heat sink or computer casing. Such passive cooling approach has many advantages, such as less power consumption, no noise generation and longer lifespan. Hence the heatpipe plays a critical role in resolving the cooling problem of notebook computers and other slim and light information products in the future.

For instance, R.O.C. patent No. 1321644 discloses a heat pipe cooling device which includes a heat pipe and a heat sink. The heat pipe includes an evaporation section, a condensation section and an insulation section bridging the evaporation section and condensation section. The evaporation section is in contact with the surface of a heating element that has a contact area substantially the same as the surface area of the heating element. The condensation section is connected to the heat sink. The evaporation section and the insulation section are connected in a tapered manner with a junction formed at a radius of curvature at a ratio greater than 0.2 and smaller than or equal to 1 against the width of the cross section of the insulation section.

The aforesaid conventional technique has a drawback that the cooling capability thereof is restricted by the volume in the heat pipe. As the smaller internal volume, the amount of working fluid held therein is also less. The heat pipe is formed in a single pipe so that it has slower cooling speed. Moreover, if the heat pipe is applied to electronic elements with super high speed, it will generate a greater amount of heat during operation and cannot achieve the cooling requirement.

SUMMARY OF THE INVENTION

The primary object of the present invention is to solve the disadvantage of undesirable cooling efficiency of the conventional technique.

To achieve the foregoing object, the present invention provides an improved heat dissipation structure adopted on an electronic element to dissipate heat thereof. The heat dissipation structure includes a heat absorber and a heat sink. The heat absorber has a contact surface connected to the electronic element to absorb heat generated thereon, and includes a hollow first chamber to hold a working fluid for transferring heat. The heat sink has a cooling surface and a hollow second chamber inside. The heat absorber and heat sink are interposed by a plurality of first conduits to connect the first chamber and second chamber. Heat generated by the electronic element is absorbed by the heat absorber through the contact surface. The working fluid held in the first chamber is heated and vaporized into vapor flowing from the first chamber via the first conduits to the second chamber. The vapor performs heat exchange with the cooling surface in the second chamber and converted into the working fluid again. The working fluid flows back to the first chamber via a second conduit containing a capillary structure inside to form a thermal cycle to carry constantly the heat of the electronic element away.

By means of the second conduit having the capillary structure, the working fluid can quickly flow back to the first chamber to form a thermal cycle. The heat absorber and heat sink have respectively the first chamber and second chamber that have greater volume to hold more working fluid. The heat dissipation structure of the invention thus formed is simpler and can dissipate heat quickly.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the heat dissipation structure of the invention.

FIG. 2 is an exploded view of the heat dissipation structure of the invention.

FIGS. 3A and 3B are sectional views of the heat dissipation structure of the invention in use conditions.

FIG. 4 is a sectional view of the capillary structure of the invention using cotton strings in a use condition.

FIG. 5 is a perspective view of an embodiment of the invention equipped with radiation fins.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 and 2, the present invention aims to provide an improved heat dissipation structure 1 mainly adopted on an electronic element 60 to dissipate heat thereof.

The heat dissipation structure 1 includes a heat absorber 10, a heat sink 20 and a plurality of first conduits 30 bridging the heat absorber 10 and heat sink 20. The heat absorber 10 is installed on the surface of the electronic element 60 to absorb heat generated thereon. The heat absorber 10 is a hollow casing containing a first chamber 12. The heat sink 20 also is a hollow casing containing a cooling surface 21 and a second chamber 22 to perform heat exchange. The heat absorber 10 and heat sink 20 have respectively a plurality of first coupling orifices 13 and second coupling orifices 23 to couple with the first conduits 30. Thus forms the main structure of the invention.

Referring to FIGS. 3A and 3B, the heat absorber 10 is mounted onto the electronic element 60 with a contact surface 11 to absorb heat generated by the electronic element 60 during operation. The first chamber 12 holds a working fluid 50 which may be a refrigerant or liquid such as pure water, methanol, ethanol, acetone or heptane in this embodiment, but not the limitation. When the electronic element 60 is in operation and generates heat, the contact surface 11 absorbs the heat from the electronic element 60 and transfers the heat to the working fluid 50 in the first chamber 12, and the temperature of the working fluid 50 rises. When the temperature of the working fluid 50 is greater than the evaporation point, the working fluid 50 is converted into vapor which enters from the first chamber 12 through the first conduits 30 to the second chamber 22 of the heat sink 20. The heat sink 20 is made of a high heat conductive material, hence when the vapor enters the second chamber 22 to contact with the cooling surface 21, the heat carried by the vapor is rapidly absorbed by the cooling surface 21 and performs heat exchange with external air so that the vapor temperature drops. When the vapor temperature drops to the condensation point, the vapor is converted into the working fluid 50 again and attached to the inner walls of the heat sink 20.

Referring to FIG. 3B, the heat dissipation structure 1 further has a second conduit 40 containing a plurality of capillary structures 41 which can be fine grooves, metal fibers, sintered powders, metal meshes, or cotton fabrics or the like, but these are not the limitations. Any capillary structure with adsorption capability shall be included in the scope of the invention. The second conduit 40 has two ends formed respectively a flow conduction portion 42 which is formed in a chamfer shape to allow the working fluid 50 to flow into the second conduit 40 more smoothly. The condensed working fluid 50 flows along an inclined wall 24 of the heat sink 20. The inclined wall 24 is inclined downwards from one edge thereof towards the second conduit 40 so that the working fluid 50 can quickly flow towards the second conduit 40 to accelerate cycling speed. Moreover, the working fluid 50 is absorbed by the capillary structures 41 and flowed back to the first chamber 12 to continuously absorb the heat generated by the electronic element 60 to form a thermal cycle. Thereby the electronic element 60 can be maintained at a desired working temperature in regular conditions.

Please refer to FIG. 4 for an embodiment of the capillary structures 41 which are made of cotton strings. The capillary structures 41 made of the cotton strings are held in the second conduit 40. When the vapor is condensed into the working fluid 50 in the second chamber 22, the working fluid 50 flows along the inclined wall 24 towards the second conduit 40. The capillary structures 41 absorb the working fluid 50 and convey it through the second conduit 40 to the first chamber 12 to form the thermal cycle.

To enhance cooling efficiency, the invention provides another embodiment that includes a radiation fin 70 as shown in FIG. 5. The radiation fin 70 is located on the cooling surface 21 of the heat sink 20 and made of a high heat dissipating material such as aluminum or copper with a plurality of grooves formed on the surface thereof. Such a structure not only can increase cooling area, but also can channel air to circulate therein so that cooling effect of the heat sink 20 can be further enhanced to improve the cooling function of the invention.

As a conclusion, the invention provides the capillary structures 41 in the second conduit 40 to rapidly convey the working fluid 50 back to the first chamber 12 to continue the thermal cycle. The structure of the invention is simpler and cooling can be accomplished rapidly.

While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention. 

1. A heat dissipation structure for dissipating heat from an electronic element, comprising: a heat absorber which includes a contact surface connected to the electronic element and a hollow first chamber to hold a working fluid, the heat absorber absorbing heat generated by the electronic element through the contact surface and transferring the heat to the working fluid to be vaporized into vapor; a heat sink which includes a cooling surface and a hollow second chamber; and a plurality of first conduits and a second conduit that respectively communicate with the first chamber and the second chamber, the vapor entering the second chamber through the first conduits and being in contact with the cooling surface to perform heat exchange to be condensed into the working fluid again; the second conduit holding a capillary structure to convey the condensed working fluid from the second chamber to the first chamber to form a thermal cycle.
 2. The heat dissipation structure of claim 1, wherein the capillary structure is selected from the group consisting of sintered powders, metal fibers, metal meshes, grooves and cotton fabrics.
 3. The heat dissipation structure of claim 1, wherein the cooling surface of the heat sink is connected with a radiation fin.
 4. The heat dissipation structure of claim 1, wherein the working fluid is a refrigerant.
 5. The heat dissipation structure of claim 1, wherein the working fluid is selected from the group consisting of pure water, methanol, ethanol, acetone and heptane.
 6. The heat dissipation structure of claim 1, wherein the second conduit includes two ends formed respectively a flow conduction portion which is formed in a chamfer shape to facilitate flowing of the working fluid into the second conduit.
 7. The heat dissipation structure of claim 1, wherein the heat absorber and the heat sink include respectively a plurality of first coupling orifices and second coupling orifices to respectively connect with the first conduits and the second conduit.
 8. The heat dissipation structure of claim 7, wherein the heat sink includes an inclined wall inclined downwards from one edge thereof towards the second coupling orifices. 